1. Field of the Invention
The invention relates to a receiving method and a receiving apparatus which are suitable for reception of a radio signal transmitted by CDMA (Code Division Multiple Access), for example. More particularly, this invention relates to a technique suitable for the reception in environment where fading occurs.
2. Description of the Related Art
Heretofore, an approach has been adopted in order to excellently receive a radio signal transmitted by CDMA in a multipath environment where fading occurs, such as a mobile unit. This approach is that a plurality of paths are separately received by a plurality of receive sections in a receiver and then a plurality of received paths are combined with one another, whereby received data is obtained. Receiving is performed by combining such a plurality of paths with one another, whereby good receiving properties are ensured even in the multipath environment.
On the other hand, the path frequently is suddenly present moves or disappears in the multipath environment where the fading occurs. To obtain the received data by the above-mentioned combination of a plurality of paths in such a multipath environment, it is important to appropriately select a plurality of paths. However, it cannot be necessarily said that the conventional receiving can appropriately select the path. That is, it is difficult to resolve the path having the time shorter than resolution of a symbol rate of the transmitted data, for example. During the reception and combination of each multipath, the received data with timing closer than the symbol rate becomes redundant and thus a useless combination takes place. Moreover, a circuit for receiving each path may receive the paths with the same timing. Also in such a case, the useless combination occurs.
The reception of the signal transmitted by CDMA has been described above as an example. However, the same problem exists when the radio transmitted signal digital-modulated by various types of schemes is received in the environment where the fading occurs.
It is an object of the invention to enable only a valid path to be appropriately selected and received in receiving a multipath signal.
A receiving method of the invention comprises the steps of: prioritizing a plurality of received paths; setting an inhibition timing region having a predetermined time interval in a section before and after at least the highest-priority received path in accordance with the result of prioritization; and inhibiting the other received paths from being obtained in the set inhibition timing region. Therefore, each received path is always received with valid timing. Moreover, the setting of reception timing by timing setting means is controlled so that the other received paths may not be present in the set inhibition timing region, whereby the reception timings of a plurality of receiving means are always set to valid timings.